Tradeoffs in designing networks with end-to-end statistical QoS guarantees

Recent research on statistical multiplexing has provided many new insights into the achievable multiplexing gain in QoS networks, however, generally only in terms of the gain experienced at a single switch. Evaluating the statistical multiplexing gain in a general network remains a difficult challenge. In this paper we describe two distinct network designs for statistical end-to-end delay guarantees, referred to as class-level aggregation and path-level aggregation, and compare the achievable statistical multiplexing gain. Each of the designs presents a particular trade-off between the attainable statistical multiplexing gain and the ability to support delay guarantees. The key characteristic of both designs is that they do not require, and instead, intentionally avoid, consideration of the correlation between flows at multiplexing points inside the network. Numerical examples are presented for a comparison of the two designs. The presented class-level aggregation design is shown to yield very high achievable link utilizations while simultaneously achieving the desired statistical guarantees on delay.